Recently, various types of information display devices such as smartphones and tablet computers which users hold by the hands to check displayed information are devised.
Such an information display device generally receives an input of an operation from a user's finger while the user holds the information display device body by the hand. Further, as this operation input means, a touch panel which is overlaid and arranged on a flat display on a surface of the information display device is usually used. In this case, the user touches the touch panel on a display screen by the finger to input an operation.
Further, conventionally, information display devices which each have a touch panel on a display screen as well as a touch pad on a back surface side are also devised as disclosed in, for example, Patent Literatures 1 and 2.
The touch pads on the back surface side of the information display devices disclosed in Patent Literatures 1 and 2 are used for auxiliary input of an operation through the touch panel on the top surface side.
Patent Literature 1: Japanese Patent Application Laid-Open No. 2010-108061
Patent Literature 2: Japanese Patent Application Laid-Open No. 2010-140417
As described above with reference to the conventional technique, the information display device mainly receives an input of an operation through the touch panel on the surface, and the touch panel is frequently touched and therefore is very likely to become dirty due to a finger oil and visibility of the display screen lowers. Further, to prevent the touch panel from becoming dirty, wiping stains on the display screen needs to be frequently performed and is bothersome for users.
Furthermore, a conventional technique has difficulty in realizing a complex operation input using the touch pad on the back surface side in the information display device which has a touch pad on the back surface side unlike the touch panel on the top surface side. Still further, a more complex detection mechanism is required to enable such a complex operation input, and therefore the information display device becomes larger.